Impact of etelcalcetide on fibroblast growth factor-23 and calciprotein particles in patients with secondary hyperparathyroidism undergoing haemodialysis

Aim Recently, we demonstrated the efficacy of etelcalcetide in the control of secondary hyperparathyroidism (SHPT). This post hoc analysis aimed to evaluate changes in fibroblast growth factor-23 (FGF23) and calciprotein particles (CPPs) after treatment with calcimimetics. Methods The DUET trial was a 12-week multicenter, open-label, parallel-group, randomized (1:1:1) study with patients treated with etelcalcetide plus active vitamin D (E + D group; n = 41), etelcalcetide plus oral calcium (E + Ca group; n = 41), or control (C group; n = 42) under maintenance haemodialysis. Serum levels of FGF23 and CPPs were measured at baseline, and 6 and 12 weeks after the start. Results In the linear mixed model, serum levels of FGF23 in etelcalcetide users were significantly lower than those in non-users at week 6 (p < .001) and week 12 (p < .001). When compared the difference between the E + Ca group and the E + D group, serum levels of FGF23 in the E + Ca group were significantly lower than those in the E + D group at week 12 (p = .017). There were no significant differences in the serum levels of CPPs between etelcalcetide users and non-users at week 6 and week 12, while CPPs in the E + Ca group were significantly lower than those in the E + D group (p < .001) at week 12. Conclusion Etelcalcetide may be useful through suppression of FGF23 levels among haemodialysis patients with SHPT. When correcting hypocalcaemia, loading oral calcium preparations could be more advantageous than active vitamin D for the suppression of both FGF23 and CPPs.